Simple considerations on the deflection angle of light in General Relativity

The purpose of this paper is to provide an easy to approach yet complete discussion on the relativistic de?ection of light. First, we obtain the formula for the deflection of light in the Friedmann-Roberson-Walker metric. We then show this result is equivalent to the equation for the path of a light ray in a medium with a certain effective index of refraction. Finally we compare the angle of deflection in the potential of a point-like mass with the one that might be obtained via simple classical-limit considerations.